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[1/1] i2c: nvidia-gpu: Handle timeout correctly in gpu_i2c_check_status()

Message ID 20200326130502.10266-2-kai.heng.feng@canonical.com
State New
Headers show
Series Fix Nvidia's ucsi_ccg to make system be able to sleep | expand

Commit Message

Kai-Heng Feng March 26, 2020, 1:05 p.m. UTC
BugLink: https://bugs.launchpad.net/bugs/1850238

Nvidia card may come with a "phantom" UCSI device, and its driver gets
stuck in probe routine, prevents any system PM operations like suspend.

There's an unaccounted case that the target time can equal to jiffies in
gpu_i2c_check_status(), let's solve that by using readl_poll_timeout()
instead of jiffies comparison functions.

Fixes: c71bcdcb42a7 ("i2c: add i2c bus driver for NVIDIA GPU")
Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Ajay Gupta <ajayg@nvidia.com>
Tested-by: Ajay Gupta <ajayg@nvidia.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
(cherry picked from commit d944b27df121e2ee854a6c2fad13d6c6300792d4 linux-next)
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
 drivers/i2c/busses/i2c-nvidia-gpu.c | 20 ++++++++------------
 1 file changed, 8 insertions(+), 12 deletions(-)

Comments

Kleber Souza March 31, 2020, 9:36 a.m. UTC | #1
On 26.03.20 14:05, Kai-Heng Feng wrote:
> BugLink: https://bugs.launchpad.net/bugs/1850238
> 
> Nvidia card may come with a "phantom" UCSI device, and its driver gets
> stuck in probe routine, prevents any system PM operations like suspend.
> 
> There's an unaccounted case that the target time can equal to jiffies in
> gpu_i2c_check_status(), let's solve that by using readl_poll_timeout()
> instead of jiffies comparison functions.
> 
> Fixes: c71bcdcb42a7 ("i2c: add i2c bus driver for NVIDIA GPU")
> Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Reviewed-by: Ajay Gupta <ajayg@nvidia.com>
> Tested-by: Ajay Gupta <ajayg@nvidia.com>
> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
> (cherry picked from commit d944b27df121e2ee854a6c2fad13d6c6300792d4 linux-next)

This patch has already been merged to Linus' tree with the same sha1,
the 'linux-next' part can be removed.

Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> ---
>  drivers/i2c/busses/i2c-nvidia-gpu.c | 20 ++++++++------------
>  1 file changed, 8 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-nvidia-gpu.c b/drivers/i2c/busses/i2c-nvidia-gpu.c
> index 5a1235fd86bb..32cd62188a3d 100644
> --- a/drivers/i2c/busses/i2c-nvidia-gpu.c
> +++ b/drivers/i2c/busses/i2c-nvidia-gpu.c
> @@ -8,6 +8,7 @@
>  #include <linux/delay.h>
>  #include <linux/i2c.h>
>  #include <linux/interrupt.h>
> +#include <linux/iopoll.h>
>  #include <linux/module.h>
>  #include <linux/pci.h>
>  #include <linux/platform_device.h>
> @@ -75,20 +76,15 @@ static void gpu_enable_i2c_bus(struct gpu_i2c_dev *i2cd)
>  
>  static int gpu_i2c_check_status(struct gpu_i2c_dev *i2cd)
>  {
> -	unsigned long target = jiffies + msecs_to_jiffies(1000);
>  	u32 val;
> +	int ret;
>  
> -	do {
> -		val = readl(i2cd->regs + I2C_MST_CNTL);
> -		if (!(val & I2C_MST_CNTL_CYCLE_TRIGGER))
> -			break;
> -		if ((val & I2C_MST_CNTL_STATUS) !=
> -				I2C_MST_CNTL_STATUS_BUS_BUSY)
> -			break;
> -		usleep_range(500, 600);
> -	} while (time_is_after_jiffies(target));
> -
> -	if (time_is_before_jiffies(target)) {
> +	ret = readl_poll_timeout(i2cd->regs + I2C_MST_CNTL, val,
> +				 !(val & I2C_MST_CNTL_CYCLE_TRIGGER) ||
> +				 (val & I2C_MST_CNTL_STATUS) != I2C_MST_CNTL_STATUS_BUS_BUSY,
> +				 500, 1000 * USEC_PER_MSEC);
> +
> +	if (ret) {
>  		dev_err(i2cd->dev, "i2c timeout error %x\n", val);
>  		return -ETIMEDOUT;
>  	}
>
diff mbox series

Patch

diff --git a/drivers/i2c/busses/i2c-nvidia-gpu.c b/drivers/i2c/busses/i2c-nvidia-gpu.c
index 5a1235fd86bb..32cd62188a3d 100644
--- a/drivers/i2c/busses/i2c-nvidia-gpu.c
+++ b/drivers/i2c/busses/i2c-nvidia-gpu.c
@@ -8,6 +8,7 @@ 
 #include <linux/delay.h>
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
+#include <linux/iopoll.h>
 #include <linux/module.h>
 #include <linux/pci.h>
 #include <linux/platform_device.h>
@@ -75,20 +76,15 @@  static void gpu_enable_i2c_bus(struct gpu_i2c_dev *i2cd)
 
 static int gpu_i2c_check_status(struct gpu_i2c_dev *i2cd)
 {
-	unsigned long target = jiffies + msecs_to_jiffies(1000);
 	u32 val;
+	int ret;
 
-	do {
-		val = readl(i2cd->regs + I2C_MST_CNTL);
-		if (!(val & I2C_MST_CNTL_CYCLE_TRIGGER))
-			break;
-		if ((val & I2C_MST_CNTL_STATUS) !=
-				I2C_MST_CNTL_STATUS_BUS_BUSY)
-			break;
-		usleep_range(500, 600);
-	} while (time_is_after_jiffies(target));
-
-	if (time_is_before_jiffies(target)) {
+	ret = readl_poll_timeout(i2cd->regs + I2C_MST_CNTL, val,
+				 !(val & I2C_MST_CNTL_CYCLE_TRIGGER) ||
+				 (val & I2C_MST_CNTL_STATUS) != I2C_MST_CNTL_STATUS_BUS_BUSY,
+				 500, 1000 * USEC_PER_MSEC);
+
+	if (ret) {
 		dev_err(i2cd->dev, "i2c timeout error %x\n", val);
 		return -ETIMEDOUT;
 	}